It is desirable to have a television receiver which is capable of receiving not only television signals, but also broadcast FM radio signals. In the United States, the broadcast FM band occupies a band of frequencies extending from approximately 88 MHz to approximately 108 MHz. This band of frequencies lies between the frequencies allocated for broadcast television channel 6 and television cable channel 98. Modern intercarrier-sound-type television receivers having the capability to receive broadcast FM signals are known from the prior art. However, in these known arrangements, their respective manufacturers added a separate FM radio having its own tuner. This may have been done because television tuners commonly include tuned circuits (FM traps) for trapping out FM signals which may otherwise interfere with television signal reception.
A typical FM trap for a television receiver is a tuned circuit exhibiting an amplitude vs. frequency characteristic having a single deep notch substantially centered on the FM band of frequencies, and sufficiently wide to attenuate FM signals throughout the FM band of frequencies. Not surprisingly, removing the FM trap degrades the performance of the receiver when tuning television signals. This is deemed unaceptable because the receiver is primarily a television receiver, and only additionally an FM radio receiver. Providing an electronically switchable FM trap is also deemed unacceptable because it adds to the expense and complexity of the receiver design, and may cause performance degradation of its own, due to stray capacitances and stray inductances which may be introduced.